It is known that the navigation and operation of aircraft, in particular of civil transport airplanes, may give rise to considerable work loads for the crews and the air traffic control. In particular, certain flight phases or conditions may be apt to engender greater or lesser dispersion of the attention of pilots. The complex synthesis of piloting and navigation data and of the states of the aircraft's systems may then not take place in an optimal and complete manner. The construction of false mental images of the actual situation of the aircraft in space, in particular as regards the vertical margins with respect to the terrain, may be the cause of untimely or erroneous judgements and behaviors.
Furthermore, during the use of flight management computers (for example of “FMS” type: “Flight Management System”), difficulties may appear in the programming and analysis of the flight plan confirmed by the crew. Awareness of the trajectory piloted by the automatic facilities in relation to the outside environment is not immediate. The programming gives rise itself to a sizeable workload. It may also be erroneous, with awareness of the error coming later.
The two points mentioned above, namely, on the one hand, the lack of awareness of the vertical margins of the aircraft and, on the other hand, the difficulties in dialogue and in programming the flight management computers, may sometimes be the cause of accidents of the aircraft by contact with the terrain. These two points may be characterized by an overall lack of situational awareness. Situational awareness is a synthesis of mental models constantly updated by cognitive and physical activities. The performance of the automatic facilities may aid the crew during a situation of risk, but rarely increases the situational awareness of the pilots. Moreover, improvement of the situational awareness generally demands a considerable mental effort. The civil aviation sector is therefore seeking simple and intuitive means for aiding pilots to instantaneously ascertain the position of the aircraft in its environment, at the present instant and in the minutes to come.